Spatial data analysis ranges from the visualization and exploration of
spatial data, through spatial statistics to spatial econometrics. The
techniques involved are intended to explore for and demonstrate the
presence of dependence between observations in space (Bivand,
1998). As it has been already mentioned, two types of spatial effects
are of particular interest as they have considerable influence in analysis
of data that are spatially referenced: spatial autocorrelation and spatial
heterogeneity